Polyelectrolytes
hydrogels, Super Absorbents

Properties and Applications

Polyelctrolytes resins are watersoluble polymers carrying ionizable or ionic groups. Their properties are similar to both electrolytes and polymers. Like regular salts, acids, and bases, their solutions are electrically conductive and like polymers, their viscosity strongly depends on the molecular weight and polymer concentration.
Both natural and synthetic polyelectrolytes are manufactured on a large scale. Common natural polyelectrolytes are pectin (polygalacturonic acid), alginate (alginic acid), xanthan gum, and polypeptides (proteins). Examples of common (semi-)synthetic polyelectrolytes are polyacrylic acid, polystyrene sulfonate, carboxymethyl cellulose and their salts.

Polyelectrolytes have many applications mostly related to modifying flow, improving the stability of aqueous colloids and gels or inducing agglomeration. For instance, they can be used to initiate flocculation and precipitation. They can also be used to impart a surface charge to neutral particles, enabling them to be dispersed in an aqueous solution. They are thus often used as thickeners, dispersant agents, conditioners, emulsifiers, ion-exchanger and clarifying agents. Because polyelectrolytes are water-soluble, they are also used in biochemical and medical applications such as implant coatings and controlled drug release systems. Large quantities of slightly cross-linked sodium polyacrylate-polyacrylamide copolymers, called hydrogels, are used as super absorbents (SAPs). The largest use of SAPs is found in baby diapers and other personal disposable hygiene products, such as adult protective underwear and sanitary napkins.